Carbon foam and high density carbon foam composite tooling

ABSTRACT

Tools for the forming of composite parts from composite forming materials, having tool bodies that comprise, at least in part, carbon foam and high density carbon foam are described. In some embodiments, a surface of the carbon foam or high density carbon foam may comprise a tool face. In other embodiments, the carbon foam or high density carbon foam may support an other material, referred to as tool face material, wherein a surface of the tool face material may comprise a tool face. The tools of the present invention may be lighter, more durable, and less costly to produce and/or use than conventional tools used for the production of composite parts, particularly those tools used for the production of carbon composites. Additionally, such tools may be reusable, repairable, and more readily modifiable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/619,223, filed Jan. 3, 2007 entitled “SimultaneousProduction of High Density Carbon Foam Sections” which is acontinuation-in-part of U.S. patent application Ser. No. 11/393,308,filed Mar. 30, 2006 entitled “High Density Carbon Foam”, which is basedon U.S. Provisional Patent Application No. 60/594,355, filed on Mar. 31,2005, and which all above referenced applications are hereinspecifically incorporated by reference in their entireties.

FIELD OF THE INVENTION

This invention relates to composite tooling and methods for using thesame, more specifically incorporating carbon foam and high densitycarbon foam in a tool body for forming parts made from compositematerials.

BRIEF BACKGROUND OF THE INVENTION

Generally, composite materials are prepared by imbedding a reinforcingmaterial within a matrix material. Composite materials having highdegrees of utility typically exhibit mechanical or other propertiessuperior to those of the individual materials from which the compositewas formed. A common example of a composite material is fiberglass.Fiberglass is glass fibers, which are the reinforcing material, embeddedin a cured resin, which constitutes the matrix material.

Composite materials have been found to have a high degree of utilitywhen used as parts of structures, components, sub assemblies, and thelike, of assemblages such as aircraft, missiles, boats, medicalequipment, and sporting goods. A composite commonly used in suchapplications is fiberglass. Other composites having particularly highdegrees of utility in such applications are those that are prepared fromcarbon fibers combined with a matrix material such as thermoset (e.g.thermosetting and the like) and/or thermoplastic resins. Such compositesare referred to as carbon fiber composites (herein after referred to asCFC), or more commonly, carbon composites. Carbon composites have beenused, for example, as aircraft flight surfaces, missile bodies,orthopedic supports, and golf club shafts. The utility of such carboncomposites is typically related to their exceptionally high strength toweight ratio and their fatigue and corrosion resistance. In mostinstances, these beneficial properties exceed those of the metals orother materials supplanted by the use of the carbon composites.Additionally, some types of carbon fiber composites can be carbonized toform carbon-carbon composites.

Specific fiber orientations may be desired in the final compositeproduct to impart accentuated strength, stiffness, and/or flexibilityalong certain axes. Furthermore, composite forming materials,particularly carbon fiber, are relatively expensive and wastage isgenerally discouraged. For these and other reasons, composites areproduced in sizes, shapes, and forms that closely match those requiredby the intended application. In fact, composites, particularly carbonfiber composites used in aerospace and many other applications, areroutinely produced, within very restrictive tolerances, to the requiredsize.

The forming of composites, including carbon composites, to such highdimensional requirements is typically accomplished by the use of moldlike devices commonly referred to as tools. These tools encompass one ormore surfaces, referred to as tool faces, upon which the composite isformed, shaped, molded, or otherwise produced into components ofpredetermined sizes and shapes. Such components can include structures,parts, sub assemblies and the like, and may be referred to collectivelyas parts. The tool face is a surface typically formed such that it is aprecise three dimensional negative mirror image of a surface of thedesired composite component. That is, a raised surface on the compositepart will be matched and formed by an equivalently (negatively)dimensioned surface depression of the tool face. Likewise, a recessedsurface on the composite part will be matched and formed by anequivalently (negatively) dimensioned raised surface of the tool face.In practice, a mixture of a reinforcing material and a matrix material,for example carbon fiber and a resin, are placed upon the tool face byany number of procedures and brought into intimate contact with thattool face. The dimensions of the tool face are such that this contacteffectively molds a surface of the matrix material and reinforcingmaterial mixture into the desired shape and dimensions. The matrixmaterial is then solidified, typically by curing of the resin, toproduce the composite component. For example, a carbon fiber containingresin is cured, typically by the application of heat, to yield a solidCFC component having a surface exhibiting the shape and dimensionsimparted by the tool face.

In addition to the tool face, a tool is also comprised of a tool bodyand sometimes a support structure. The tool body comprises the toolface. That is, the tool face upon which the composite, for example aCFC, is formed is a surface of the tool body. The tool body may alsoencompass a cover which minimally encloses the tool face, or a portionthereof, such that an essentially closed volume is formed between thetool face and the cover. The support structure may be connected to thetool body and may serve a number of purposes, including but not limitedto, support, orientation, and transportation of the tool body and facealong with protection of the tool body and face from damage.

Important characteristics of tooling include, for example, quality,dimensional accuracy, weight, strength, size, cost, ease of repair, andthe like. Additionally, rigidity and durability are considered to bevery important characteristics of tooling. All of these characteristicsare dependent on the tool design, the materials of construction of thetool, and on the materials used to form the composite.

A characteristic of the tooling that may be very important is thecoefficient of thermal expansion (herein after referred to as CTE andCTEs in the plural form) exhibited by the tool face. As the tool face isa surface of the tool body, the CTE exhibited by the tool face isdependent on the material of which the tool body is comprised. It isgenerally desired that the tool face exhibit a CTE that is substantiallysimilar or equivalent to the CTE of the formed composite component(which may also be referred to as a composite part, or more simply part)formed thereon. Preferably, the CTE exhibited by the tool face should besubstantially similar or equivalent to the CTE of the formed compositepart over a wide temperature range. The importance of having asubstantial similarity, or more preferably equivalence, between the CTEof the composite part and that exhibited by the tool face is related tothe manner in which composite parts are prepared using tools. That is,typically, the materials used to form the composite are placed on thetool face at room temperature. The temperature of the tool and compositeforming materials is then increased to some elevated temperature,typically such as 250° F. or more, to cure the resin of the compositematerial. Once the resin is cured, the resulting composite part, forexample a CFC, is rigid. Following resin curing, the tool face andcomposite part are cooled to room temperatures. Such exposure totemperatures significantly above room temperature is the reason it isdesired that the CTE of the tooling match that of the resultingcomposite part. For example, if the CTE of the composite part issignificantly less than that exhibited by the tool face, the compositepart may be trapped or retained on the tool by the relatively greatercontraction of the tool face dimensions with cooling. Conversely, if theCTE of the composite part is significantly greater than that exhibitedby the tool face, the part may again be retained on the tool or maydamage the tool face during contraction, or cured composite dimensionsmay differ from those of the tool face.

Typically, carbon composites have relatively low CTEs while the CTEs formost other materials are much higher. Therefore it is very difficult tomatch the CTE exhibited by the tool face with the CTE of a carboncomposite as there are few materials available for construction of thetool body that have sufficiently low CTEs. Such available low CTEmaterials suitable for construction of the tool body include, forexample, graphite, other carbon composites, INVAR® (e.g., a controlledexpansion nickel iron alloy), and the like.

INVAR® is durable and has a CTE that is substantially similar to that ofcarbon composites. However, INVAR® based tools are typically heavy,difficult to fabricate, and can require, for example, as many asseventeen separate stages to fabricate. Such numerous fabrication stagescan lead to about a 140% to about a 250% increase in tooling costs and afour fold increase in lead times, as discussed in “Fabrication andAnalysis of Invar Faced Composites for Tooling Applications”,Proceedings of Tooling Composites 93, Pasadena, Calif., which is herebyincorporated by reference in its entirety.

As with INVAR® based tooling, graphite based tooling may be capable ofmatching the CTE of CFC parts, and the like, even for example, thedifficult to match CTE of low CTE materials. However, such toolingtypically utilizes relatively large blocks of graphite. Graphite is arelatively dense material. Therefore, such tooling may be relativelymassive and possibly expensive. Additionally, such large, dense,massive, blocks of graphite may exhibit relatively high heat capacitiesand/or require extended time periods to heat and cool uniformly.

Similar to INVAR® based tooling, carbon fiber composite based toolingmay be capable of matching the CTE of CFC parts, and the like, even forexample, the difficult to match CTE of low CTE materials. For this typeof tooling, carbon fiber composites are used as the total tool bodyand/or that portion of the tool body defining the tool face. Carbonfiber composite based tooling is advantageous as such CFC based toolsare less expensive, lighter, have low thermal mass, and require shorterlead times for tool manufacturing than does conventional tooling such asthat based upon INVAR®. However, CFC based tools are usually susceptibleto damage if not handled with care, especially when composite is laidthereon. Additionally, surface degradation of CFC based tools may occuras a result of the repetition of the process cycle due to a combinationof component adhesion, CTE mismatch, and oxidative decomposition.Furthermore, any necessary repairs of CFC based tools leads to anincrease in repair and maintenance costs. Also, CFC based tools aresubject to dimensional stresses from uneven support. Such stresses maycause a loss of rigidity. Accordingly, due to the aforementionedproblems, CFC based tooling is not commonly used.

There are other important characteristics of composite tooling,particularly tooling for the production of CFC, which should also beconsidered. For example, in addition to being rigid, durable, strong,and CTE matchable, the tooling should also be low cost and easy toproduce. That is, a factor usually considered when selecting materialfor a tool body is the total number of parts to be produced. Included inthis consideration is the fact that production of large numbers of partscan more easily justify expensive tooling. Overall, however, it isgenerally accepted that rigid, strong, durable, and CTE matchabletooling, which can be easily produced at low cost, irrespective of theplanned number of parts, is desired.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention may include a tool for the production of atleast one composite part, where the tool comprises a tool body having atool face where the tool body is comprised of at least one piece ofcarbon foam and at least one piece of high density carbon foam, andwhere the tool face defines a surface that is a three dimensionalnegative mirror image of a surface of the at least one composite part.In some embodiments, a surface of the tool body defines a tool face,where a portion of the tool face is at least partially a surface of thecarbon foam comprising the tool body. In other embodiments, a surface ofsaid tool body defines a tool face, where a portion of the tool face isat least partially a surface of the high density carbon foam comprisingthe tool body.

Embodiments of the invention may also include various methods forproducing at least one composite part. Some embodiments of the methodmay comprise the steps of providing a tool body having a tool face,where the tool body is comprised of carbon foam and high density carbonfoam adhered together, and where the tool face defines a surface that isa three dimensional negative mirror image of a surface of the at leastone composite part; placing composite forming material on the tool face;and curing the composite forming material thereby producing thecomposite part. Further, embodiments of the invention may also includecomposite parts formed by the various methods for producing at lest onecomposite part.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 2 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 3 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 4 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 5 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 6 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 7 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 8 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

FIG. 9 illustrates a cross-sectional representation of a reusable toolhaving a tool body comprising carbon foam and high density carbon foam.Composite forming materials may be placed on the tool face of this toolfor the purpose of forming a composite part.

DETAILED DESCRIPTION OF THE INVENTION

The tools of the present invention have tool bodies that are comprisedat least in part of carbon foam and high density carbon foam. As usedherein, high density carbon foam may be referred to as HDCF in thesingular or plural tense.

Tooling may be used to fabricate parts, including composite parts, ofvarious types, shapes, sizes and materials with a high dimensionalaccuracy. The design of the tooling may be dependent on the desiredshape of the part to be formed, the materials used to form the part, theamount of strength and rigidity which the tooling must have to supportthe materials necessary for forming the part, and/or the method used toprovide the materials for forming the part.

Tools encompass one or more surfaces, referred to as tool faces, uponwhich composite forming material is formed, shaped, molded, or otherwiseproduced into a part(s) having a surface(s) of predetermined size andshape. Such parts can include, but are not limited to, structures, subassemblies, components, portions of components, partial components, andthe like, including any solid form having a shaped surface. The toolface is a surface of the tool body, typically formed such that it is aprecise three dimensional negative mirror image of a desired surface ofa part. That is, a raised surface on the part, for example a compositepart, will be matched and formed by an equivalently (negatively)dimensioned surface depression of the tool face. Likewise, a recessedsurface on the part will be matched and formed by an equivalently(negatively) dimensioned raised surface of the tool face.

In practice, materials comprising a composite part may be placed upon atool face by any of a number of procedures. Commonly, composites utilizea resin(s) as the matrix material and fiber as the reinforcing material.But, a resin(s) and a particulate(s) may also be used as the matrix andreinforcing material, respectively. Sometimes fiber placement is closelycontrolled such that the resulting composite part exhibits a specificfiber spacing and/or orientation. The fiber and resin may be mixed orotherwise combined prior to placement of the tool face. Alternatively,the fiber may be placed on the tool face and the resin subsequentlyinfused into the fiber by any of a number of procedures. In someinstances, prior to the placement of materials which will comprise thecomposite, the tool face may be covered with a thin sheet of material,sometimes referred to as a parting sheet or release film, which formsclosely to the tool face. Such sheets may be considered to be atemporary coating on the tool face. The surface of this sheet that isnot in contact with the tool face, that is, the outside surface of thesheet, then effectively becomes the tool face. Such sheets may be usedto protect the tool face and/or to provide for easier removal or releaseof the formed composite part. Alternatively, the materials comprisingthe composite may be prevented from bonding to the tool face by coatingthe tool face with a release agent. Release agents can include variouspolymers, including PVA, and waxes, among other materials. Release filmsmay be composed of any of a number of polymeric materials that do notbond with any of the materials comprising the composite. Many types ofrelease agents and films are known in the associated arts and may beused with the present invention.

The dimensions of the tool face may be such that a surface of thematerials comprising the composite part, commonly a fiber containingresin, is effectively molded into the desired shape and dimensions. Theresin(s) included in the materials comprising the composite part may besubsequently cured, in some instances by the application of heat, toyield a solid composite part having a surface of the shape anddimensions imparted by the tool face. It is not uncommon for such heatto be applied in an oven or autoclave. Use of an autoclave also mayprovide for the forming of composite parts at elevated pressures. Thesolid composite part so produced may then be removed from the tool face,subjected to any final shaping or other modification, and used for itsdesigned utility.

In addition to the tool face, a tool is comprised of a tool body and insome embodiments a support structure. The tool body defines the toolface. That is, the tool face upon which the composite part is formed isa surface of the tool body. The support structure, if present, isconnected to the tool body and may serve a number of purposes, includingbut not limited to, support, orientation, and transportation of the toolbody and face along with protection of the tool body and face fromdamage.

The tools of the present invention have tool bodies that are comprisedat least in part of carbon foam and HDCF. The tool bodies may becompletely or partially comprised of carbon foam and HDCF. The carbonfoam of individual tool bodies may be comprised of one or moreindividual pieces of carbon foam. Likewise, the HDCF of individual toolbodies may be comprised of one or more single pieces of HDCF.

If a tool body is comprised of two or more individual pieces of carbonfoam, at least two pieces of the carbon foam may be at least partiallybonded together. If a tool body is comprised of two or more individualpieces of HDCF, at least two pieces of the HDCF may be at leastpartially bonded together. Additionally, one or more pieces of carbonfoam and one or more pieces of HDCF comprising the tool body may be atleast partially bonded together. Such bonding together of the one ormore pieces of carbon foam and the one or more pieces of HDCF mayprovide a volume of material that may provide at least a portion of atool body. Adhesives, resins, cements, and the like may be used to bondor otherwise join the pieces. Mechanical methods, including, but notlimited to, bolting, screwing, strapping, pinning, and the like, mayalso be used to bond, or otherwise join, two or more pieces of carbonfoam and/or HDCF comprising the tool body. If partially comprised ofcarbon foam and HDCF, the tool bodies may be constructed such that theCTE of the tool face is substantially similar or equivalent to that ofthe carbon foam, HDCF, and the composite(s), particularly carbon fibercomposite(s), parts prepared thereon. If the tool body is essentiallycomprised only of carbon foam and HDCF, the carbon foam and HDCF mayhave a CTE substantially similar or essentially identical to that of acomposite, particularly a carbon fiber composite, and parts formedthereon.

The tool body may be comprised of other materials in those embodimentswherein the tool body is partially comprised of carbon foam and HDCF. Inthose embodiments, such other materials may, for example, coat or covera surface of a tool body, occupy and/or define an internal and/orexternal volume of a tool body, impregnate elements comprising a toolbody, and/or bond elements comprising the tool body together. In furtherembodiments, a surface of such other material may at least partiallydefine a tool face. In those embodiments, such other material may bereferred to as a tool face material. In some of those embodiments, thetool face material may be supported by carbon foam and/or HDCFcomprising the tool body.

In some embodiments, the carbon foam of the tool body may at leastpartially support the HDCF of the tool body. In further embodiments, theHDCF of the tool body may at least partially support the carbon foam ofthe tool body. In some other embodiments, a surface of the carbon foamand/or HDCF comprising the tool body may serve to define at least aportion of a tool face. In still other embodiments, the carbon foamand/or HDCF may serve to support other materials, having a surface whichdefines at least a portion of a tool face (i.e. tool face materials).

By defining at least a portion of the tool face, a surface of the carbonfoam, HDCF, and/or other materials has a surface geometry orconfiguration sufficient to impart the desired configuration to asurface of the composite part formed thereon. One or more surfaces ofthe carbon foam, HDCF, and/or other materials incorporated into a toolbody may be fabricated into various predetermined geometries to providefor one or more tool faces reflecting those geometries. These geometriesare then incorporated into a surface(s) of the composite part formedwith the tooling. The tool face(s) defines at least a portion of onesurface of at least one composite part formed with the tooling. A singletool may have a plurality of individual tool faces located on thesurface(s) of the tool body. Other materials comprising the tool body,which may be tool face materials, may have CTEs substantially similar oressentially identical to that of the carbon foam, the HDCF, and to thatof the composite part, particularly a carbon composite part, preparedthereon. In some embodiments, tool face materials for the production ofCFC parts may be carbon composites. The tool face materials may beutilized in an amount or form such that the observed CTE of the toolface is substantially similar or essentially equivalent to that of thecarbon foam, HDCF, and the composite part, particularly a carboncomposite part, prepared thereon.

In an embodiment of the invention, the carbon foam of the tool body, theHDCF of the tool body, other materials of the tool body, and the toolface portion of the tool body, including any tool face materials, may beselected or utilized such that they exhibit CTEs substantially similarto, or essentially equivalent, to each other and to the CTE of theresultant composite part formed on the tool face. In a furtherembodiment, at least a portion of the tool body, particularly thatportion of the tool body supporting and or defining the tool face, andthe tool face, may be comprised of materials having low CTE. Suchmaterials may include carbon foam, HDCF, and selected other materialsincluding tool face materials. The low CTE of these materials may besubstantially similar or essentially equivalent to those of some carbonfiber composites. Such tooling, comprising carbon foam and HDCF, may beparticularly useful for the fabrication of carbon fiber composites,particularly of tightly controlled dimensions.

In some embodiments, a single tool may have one or more tool facesdefined at least in part by a surface of the HDCF incorporated in thetool body. In other embodiments, a single tool may have one or more toolfaces defined at least in part by a surface of the carbon foamincorporated in the tool body. In still other embodiments, a single toolmay have one or more tool faces defined at least in part by a surface ofa tool face material which is supported by at least one of carbon foamand HDCF incorporated in the tool body.

In some embodiments, the described tool bodies comprising carbon foamand HDCF may be considered to be composite structures having at leastone tool face. Similar composite structures which do not include a toolface are described in U.S. patent application Ser. No. 11/751,651,entitled “Carbon Foam and High Density Carbon Foam Composite Assembly”filed on May 22, 2007, herein incorporated by reference in its entirety.

Carbon foams useful in tools may include virtually any carbon foam.Carbon foam is typically a strong, open cell, durable, stable, easilymachined, and relatively unreactive lightweight material. Carbon foamsare materials of very high carbon content that have appreciable voidvolume. Carbon foams are carbon materials. As such, carbon foams areprimarily comprised of (elemental) carbon. In appearance, exceptingcolor, carbon foams resemble readily available commercial plastic foams.As with plastic foams, the void volume of carbon foams is located withinnumerous empty cells. The boundaries of these cells are defined by thecarbon structure. These cells typically approximate ovoids of regular,but not necessarily uniform, size, shape, distribution, and orientation.The void volumes in these cells may directly connect to neighboring voidvolumes. Such an arrangement is referred to as an open-cell foam. Thecarbon in these foams forms a structure that is continuous in threedimensions across the material. Typically, the cells in carbon foams areof a size that is readily visible to the unaided human eye. Also, thevoid volume of carbon foams is such that it typically occupies muchgreater than one-half of the carbon foam volume. The density of carbonfoams typically is less than about 1. g/cc and generally less than about0.8 g/cc. In some embodiments, the density for carbon foam may rangefrom about 0.05 g/cc to about 0.8 g/cc. In some embodiments, carbonfoams may exhibit compressive strengths ranging up to about 10,000 psi.In other embodiments, the compressive strength for carbon foam may rangefrom about 100 psi to about 10,000 psi. In certain other embodiments,compressive strengths for carbon foam may range from about 400 psi toabout 7,000 psi. The carbon foam incorporated in a tool body may becarbonized carbon foam. Alternatively, if desired, the carbon foamincorporated in a tool body may be graphitized carbon foam.

Carbon foams may also exhibit very low coefficients of thermal expansionwhich may be essentially equivalent to those of carbon fiber composites.The CTE of carbon foam may be modified by control of the maximumtemperature to which the carbon foam is exposed during preparation or byselection of the material, and process, used for preparing carbon foam.In some embodiments, carbon foams exhibit a coefficient of thermalexpansion from about 3.5 ppm/° C. to 6.5 ppm/° C.

The regular size, shape, distribution, and orientation of the cellswithin carbon foam readily distinguish this material from other carbonmaterials such as metallurgical cokes. The void volumes within cokes arecontained in cell-like areas of typically ovoid shape and random size,distribution, and orientation. That is, in cokes, some void volumes canbe an order of magnitude, or more, larger than others. It is also notuncommon that the over-lapping of void volumes in cokes results insignificant distortions in the void shape. These distortions and largevoid volumes can even lead to a product that has limited structuralintegrity in all except smaller product volumes. That is, it is notuncommon for coke to be friable and larger pieces of coke to readilybreak into smaller pieces with very minimal handling. Such breakage istypically not exhibited by carbon foams. Also, a given sample of cokecan exhibit both open and closed-cell void volumes.

Carbon foams have been produced by a variety of methods. Some of thesemethods include producing carbon foams directly from particulate coal.For example, U.S. Pat. Nos. 6,749,652 and 6,814,765, each hereinincorporated by reference in their entirety, describe methods forproducing carbon foam directly from particulate coal. In addition toparticulate coal feedstocks, carbon foam forming feedstocks, alsoreferred to as carbon foam precursors, may include, but are not limitedto, coal, pitch, coal extracts, mesophase pitches, mesophase materials,hydrogenated coals, hydrogenated coal extracts, solvent refined coals,solvent refined coal extracts, and the like. Additionally, carbonizablepolymeric foams such as phenolic and furan foams may be carbonized toproduce carbon foam. Typically, specific, different, processes areutilized for the production of carbon foams using each type offeedstock.

HDCF is typically a strong, dense, hard, porous, durable, stable, andrelatively unreactive carbon material. In some embodiments, the densityof HDCF may be greater than about 1. g/cc. HDCF may exhibit differingsets of properties dependant on the feedstock(s) used for production,the selected production process, and any post-production treatments. Invarious embodiments, HDCF may exhibit differing degrees or magnitudesof, for example, electrical conductivity, surface hardness, CTE,density, porosity, graphitization, crush strength, and the like. In someembodiments, HDCF may exhibit very low coefficients of thermal expansionwhich may be essentially equivalent to those of carbon fiber composites.The CTE of HDCF may be modified by control of the maximum temperature towhich the HDCF is exposed during preparation or by selection of thefeedstock, and process conditions, used for preparing HDCF.

HDCF are those carbon foams that exhibit densities of about 1. g/cc orgreater. In certain embodiments, the densities may range from about 1.g/cc to about 2. g/cc. In other embodiments, the densities may rangefrom about 1.2 g/cc to about 1.8 g/cc. In still other embodiments, thedensities may range from about 1.3 g/cc to about 1.6 g/cc. HDCF, whenheated to temperatures greater than about 700° C., and more typicallygreater than about 950° C., followed by cooling to essentially ambienttemperatures, may have compressive strengths (ASTM C365) greater thanabout 5,000 lbs/in², in some embodiments greater than about 10,000lbs/in², and in other embodiments greater than about 20,000 lbs/in².Some HDCF may be electrically conductive and exhibit electricalresistivities less than about 0.002 ohm-cm. HDCF may also exhibit goodthermal transport properties. In some embodiments, the HDCF may have athermal conductivity between about 5 to 70 W/mK. In other embodiments,the HDCF exhibits an appreciable (surface) hardness. The body of theseHDCF may be largely isotropic. HDCF are materials of very high carboncontent that have limited void volume. HDCF are carbon materials. Assuch, HDCF are primarily comprised of (elemental) carbon.

To the unaided eye, HDCF may appear to be non-porous solids. However,optical microscopic examination of HDCF at 10× to 100× may show somedegree of porosity. In some embodiments, this porosity is evenlydistributed in the foam. The porosity of the HDCF provides void volumeswithin the foam that are predominately in communication with one anotherand with the exterior of the foam, thus providing a structure that maybe referred to as “open celled” or “porous”.

In some embodiments, optical microscopic examination of HDCF at amagnification of about 90× shows that the HDCF is not simply comprisedof sintered powders. That is, the vast majority of the coal particulatesfrom which the foam was prepared are predominantly no longerrecognizable as individual particles bonded together only at their areasof mutual contact, as would be the case in a sintered material. Inappearance, the microscopic structure of the HDCF may appear similar,but not equivalent, to the structures of both low density coal basedcarbon foams and reticulated vitreous carbons. That is, the HDCF may becomprised of defined, regular, void spaces delimited by thick, somewhatcurved, interconnected carbon ligaments, which result in a continuous,open-celled, foam-like dense carbon body. Typically, the void spaces ofthe HDCF do not have a high population of the wide curving walls usuallypresent in the well-defined spherical voids of lower density (densitiesless than 1. g/cc, and more typically less than 0.5 g/cc) coal basedcarbon foam. The void spaces of the HDCF materials are typicallysignificantly smaller than those observed in a typical (low-density)carbon foam material.

In other embodiments, the structure of the HDCF may appear, undermicroscopic examination at about 90×, to be comprised of numerousrandomly interconnected and intertwined small carbon ligaments of randomsize and orientation. Such interconnected ligaments are continuousthrough the HDCF. The surfaces of these ligaments may be curved andrelatively smooth, non-uniform, irregular, or even occasionally embeddedwith what may be the remains of coal particles that did not achieve ahigh degree of plastic character. In such embodiments, void spacesdefined by the ligaments may be of random size and shape with limited,if any, spherical characteristics. In some embodiments, the size andnumber of void spaces may be inversely related to the density of theHDCF. That is, higher density HDCF may exhibit fewer, and smaller, voidvolumes than do lower density HDCF. Additionally, higher density HDCFmay exhibit thicker ligaments than do lower density HDCF. While thepores sizes may vary within a single piece of HDCF, the majority of thepores have a relatively consistent pore size.

HDCF and methods for production of such foams, with emphasis on thedirect production from coal, are taught in U.S. patent application Ser.No. 11/393,308 filed Mar. 30, 2006, which is specifically hereinincorporated by reference in its entirety. The teachings of this patentapplication are expanded upon in U.S. patent application Ser. No.11/619,223, filed Jan. 3, 2007 which also is specifically hereinincorporated by reference in its entirety.

HDCF useful in the present invention may include any HDCF. Such highdensity carbon foams may be prepared from coals. In some embodiments,for example, very hard, dense, nongraphitizable HDCF, which may beprepared from lower rank agglomerating bituminous coals, may beincorporated into a tool body. In other embodiments, for example, hard,dense, graphitizable HDCF, which may be prepared from higher rankagglomerating bituminous coals, may be incorporated into a tool body.Potentially, HDCF may also be prepared from pitches, polymericmaterials, mesophase materials, coal extracts, solvent refined coals,hydrogenated coals and coal products, coal derivatives, and the like.

In some embodiments, prior to incorporation into a tool body, the HDCFmay be exposed to elevated temperatures, under an inert atmosphere,sometimes as great as about 3000° C. or more. In some embodiments, theHDCF may be partially, or fully, graphitized. In other embodiments, theHDCF may be ungraphitized. In still other embodiments, the HDCF may benongraphitzable. Depending on the planned method of use of the tool,some HDCF may be more suitable for incorporation into a given tool bodythan other HDCF. For example, in some embodiments, lower density, moreporous, HDCF may be used to support tool face materials. In otherembodiments, a surface of hard, dense, HDCF may serve as a tool face.

The tools of the present invention may be reusable, repairable, and morereadily modifiable than the tools of the prior art. That is, asreusable, the tools of the present invention may be used to sequentiallyproduce more than one composite part. The carbon foam and HDCF,comprising at least a portion of the tool body of the tools of thepresent invention, is bondable using conventional adhesives, resins,cements, and the like, and may be machined to close tolerances usingreadily available hand and/or machine tools. Such machining may be bythe use of cutting tools, particularly carbide or diamond cutting tools.Such machining may also be by the use of abrasive cutting or grindingtools. As a result of these characteristics, the tools are repairable asdamaged sections of carbon foam and/or HDCF used in a composite formingtool may be readily replaced by undamaged carbon foam and/or HDCF. Also,these characteristics of carbon foam and HDCF provide for the ability toreadily replace sections of carbon foam and HDCF used in a compositeforming tool so that sections of a tool face may be modified, asdesired, without replacement of the entire tool face. The tooling of thepresent invention can be used with, or combined with, other known typesof tooling.

In certain embodiments, the carbon foam may comprise a portion of thetool body volume with the HDCF comprising another portion of the toolbody volume. In some such embodiments, the HDCF may be supported by thecarbon foam such that at least one surface of the HDCF provides at leasta portion of the tool body outer surface. Such an at least one surfaceof the HDCF may be shaped to provide at least a portion of a tool face,or, support other materials having a surface that define at least aportion of the tool face. Such tool bodies may provide for a compositeforming tools, having HDCF tool faces, that exhibit weights (i.e.masses) much less than similarly sized tools comprised principally ofgraphite. Such tools may exhibit heat capacities significantly less thana similar sized graphite tools. Therefore such tools may be easier toheat to effect curing of the composite parts formed thereon.Additionally, such tools may have tool faces exhibiting CTE essentiallyequivalent to HDCF and some CFC. In some embodiments, such tools mayhave tool faces exhibiting CTE essentially equivalent to HDCF and someCFC, and different from that of graphite. In those embodiments, suchtools may be useful for the forming of CFC having a CTE not essentiallyequivalent to the CTE of graphite, and may therefore be difficult toform on a graphite tool.

In those embodiments where a surface of the HDCF comprising the toolbody may define a tool face, the use of a hard, dense HDCF may providefor a tool face that resists damage from impacts and use. In embodimentswhere the HDCF comprising the tool body supports carbon foam or a toolface material, a less dense HDCF may be preferred to provide a moreporous surface for bonding with adhesive, resins, cements, and the like,and/or to reduce tool weight.

In certain embodiments, the HDCF comprising the tool body may supportcarbon foam or other materials having a surface that defines a toolface. In some such embodiments, the carbon foam may be supported by theHDCF such that at least one surface of the carbon foam provides at leasta portion of the tool body outer surface. Such an at least one surfaceof the carbon foam may be shaped to provide at least a portion of a toolface, or, support other materials having a surface that define at leasta portion of the tool face. In such embodiments, the HDCF may providefor a tool body having significant strength and/or rigidity. The HDCFmay also provide for a tool face having significant rigidity.

In another embodiment of the present invention, other material, whichmay be referred to as tool face material, may be formed, deposited,coated, layered, fixed, or otherwise placed on a surface of the carbonfoam or HDCF of the tool body, to provide at least a portion of a toolface. Relatively thick or relatively thin layers of tool facematerial(s) may be used, depending on the properties of the tool facematerial and the intended uses of the surface to which the tool facematerial is applied. The tool face material may cover the entire toolface. Tool face material may also cover surfaces of the tool body thatare not tool faces. Tool face material covered non-tool face surfacesmay contact the resin or other materials used for forming the compositepart. The carbon foam or HDCF may be machined or otherwise contoured orformed to produce a surface having a specific shape prior to the formingand/or depositing of the tool face material. Forming or depositing thetool face material on such a shape may then produce a tool face havingthe desired configuration and dimensions. Alternatively, after formingand/or deposition of the tool face material on the carbon foam or HDCFsurface, this material may then be machined or otherwise formed orcontoured to provide a tool face of the desired geometry. Machining ofthe HDCF, carbon foam, or tool face material may be more preciselycontrolled to the desired dimensions by incorporating witness marks,index pins, or the like, into or on the tool body prior to theinitiation of any precision machining operation.

The use of a tool face material may provide for a very smooth tool faceof high dimensional accuracy. The use of tool face materials may alsoprovide for easier removal of the formed composite part. Typically,parting films or release agents may be used with the tool faces providedby tool face materials. Additionally, the CTE of a tool face materialmay be matched with the CTE of the resultant composite part and/or withthe portion of the tool body supporting the tool face material. Suchmatching may insure the dimensional and structural accuracy andprecision of the formed composite part. Additionally, such matching mayprovide for post curing of parts on or in the tool, as opposed to freestanding curing. In certain embodiments, the CTE of the tool body, toolface, tool face materials, and composite part are substantially similaror essentially equivalent.

The term “substantially similar” CTEs as used herein, may refer to CTEvalues that are sufficiently close in magnitude that the producedcomposite part has the desired critical dimensions and is not trapped orretained in, or sprung from, the tool by the effect of non-equivalentexpansions and contractions of the composite part and tool face, or, arethose having values that are sufficiently close in magnitude that thetool face is not damaged by the effect of non-equivalent expansions andcontractions of the composite part and tool face. If the CTE of the toolface material(s) does not match the CTE of the underlying HDCF and/orcarbon foam, the tool face may exhibit a CTE between those of the twomaterials. It is anticipated that such an occurrence may provide amethod achieving a tool face CTE that is not readily obtained by othermethods. It is also anticipated that tool faces composed of thin layersof tool face materials may exhibit the CTE of the underlying carbon foamor HDCF. This would especially be expected to occur with very thinlayers of tool face materials having some elastic properties.

A number of different materials may be used, alone or in combination, asthe tool face material. These materials include, for example, curedresins, including phenolic, polyimide, BMI, and epoxy resins, prepegs,adhesive films, coatings, and the like, either alone or in combination.The tool face material may also be, for example, a composite, includingthose of fiberglass, carbon fiber, carbon-carbon, and other similarmaterials including other fiber and particulate composites.Additionally, the tool face material may be INVAR®, silicon carbide,zirconia ceramics, carbon, and other metals and ceramics. Such types ofadditional tool face materials may be deposited on the carbon foamand/or HDCF to form a tool face using techniques including, but notlimited to, arc and flame spraying and vapor deposition. Suitable toolface materials may be essentially gas impermeable. Metals, ceramics, andcarbon composites having low CTEs may be particularly useful tool facematerials, especially for those tools used to produce CFC.

In some embodiments, for some HDCF tool faces, the use of a releasecompound may be necessary to prevent bonding of the composite formingmaterials to the HDCF. In other embodiments, the use of a parting filmmay be required to prevent bonding of the composite forming materials tothe carbon foam or HDCF having a surface defining the tool face. Evenwith the use of a parting film, the porosity in some HDCF or the cellsize of the carbon foam may be reflected in the possible surfacepatterning of the resultant composite part. This impact of thispatterning may be reduced or eliminated by the use of essentiallynon-porous, dense, HDCF or carbon foams having smaller cell sizes.Carbon foams of different cell sizes, or HDCF of different porosities,may be utilized in a single tool body. For example, a small cell foam,or a low porosity HDCF, may be used to define the tool face while alighter, large cell foam, or a higher porosity HDCF, may be used tosupport the denser carbon foam, or lower porosity HDCF, defining thetool face. Alternatively, a tool face may incorporate surfaces of bothsmall cell and large cell carbon foam and/or high and low porosity HDCF.The surface pattering of the resultant composite part will then reflectthe use of carbon foams of different cell sizes and/or the HDCF ofdifferent porosities.

Such surface pattering may also be minimized or eliminated by loading,that is filling, the porosity of the HDCF and/or filling the cells, thatis, the internal void volume, of the carbon foam, with a fillingmaterial. Filling materials may include, but are not limited to curedresins, pitches, cured moldable ceramics, and the like. Some fillingmaterials, including but not limited to some cured resins and pitches,tars, and the like, may also be carbonized to produce a carbon fillingmaterial. The porosity of the HDCF and/or carbon foam may be partiallyor completely filled with the filling material. For example, only thevolume of the carbon foam or HDCF that is closest to the tool face maybe filled with the filling material. Alternatively, a fraction of, orthe entire, internal void volume of the carbon foam or porosity of theHDCF may be filled. For carbon foam, such filling may be complete suchthat each cell is completely loaded with filling material or may beincomplete such that each cell is only partially filled with the fillingmaterial. Similarly, the porosity of a given volume of HDCF may beessentially totally or partially filled. Partial filling of the carbonfoam cells or HDCF porosity will minimize pattering. In someembodiments, a smooth tool face will be provided by the complete fillingof the carbon foam cells and/or porosity of the HDCF, minimally at thetool face surface. Additionally, a smoother surface may provide for theuse of a release agent, in place of a parting film, to prevent thebonding of the composite forming materials to the tool face. Completefilling of the carbon foam cells or HDCF porosity in some volume ofcarbon foam or HDCF surrounding the tool face, possibly includingfilling of the carbon foam cells or HDCF porosity at the tool facesurface, with a gas impermeable filling material may be required forthose instances where it is desired that a vacuum be produced above thetool face. Additionally, the porosity of the HDCF and/or carbon foamcells may be partially or completely filled with a filling material toincrease the mechanical properties, such as strength, of the carbon foamand/or HDCF.

A vacuum may be produced within a carbon foam and HDCF tool body to aidin the placement of resin and/or resin based composite tool facematerials. Additionally, any undesired surface porosity exhibited by anytool face material after placement on the tool body may be filled bycoating the tool face material with a thin layer of resin. Permeation ofsuch thin resin layers into any tool face material surface porosity maybe aided by the production of a vacuum within the carbon foam and HDCFtool body.

The tool face may also be formed such that it imparts a texture to asurface of the composite part formed by the tooling. The tool face maybe inscribed with a dimensionally negative pattern such that thepositive image of this pattern will be imparted to a surface of theformed composite part. Such patterns may include any combination of aplurality of different textures, cross-hatching, scribe-lines, and thelike for establishing an outside shape and/or imparting texture to acomposite part formed thereon. Additionally, the tool face(s) surfacemay not be homogeneous. For example, one portion of the tool face(s) hasa first texture while other portions of the tool face have differenttextures.

Tool body geometries may be of a mandrel like shape. For such toolbodies, the tool face would then be the outer surface of this mandrellike shape. For example, resin impregnated paper, fabric, fiber, and thelike, may then be placed upon the surface of the mandrel (i.e. the toolface) by manual or automatic means to form a composite part having asurface, typically an interior surface, the dimensions of which mirrorthose of the outer mandrel surface.

Also, the tool faces may be in the form of a male part and/or a femalepart having cavities and/or projections with opposite shapes on opposingtool faces. In the present invention, at least a portion of one of theopposing tool faces is defined by the carbon foam or HDCF incorporatedin the tool body, or is defined by a surface of a tool face materialsupported at least in part by the carbon foam or HDCF of the tool body.A void volume between such opposing tool faces may be filled withcomposite forming materials. After curing of these materials, the shapeof the resultant composite part will duplicate that of the void volumebetween the male and female tool faces. It is also possible to have asingle tool body having at least one surface providing a tool face orone surface of the walls of a cavity serving as a tool face(s). A covermay be incorporated in the tool body. Such a cover may be a flexiblecover, where the cover may be comprised of a plastic, an elastomericmaterial, such as a silicon elastomer sheet or membrane, or otherflexible sheet like material. The cover may be placed over the surfaceor cavity to form a closed volume. A vacuum may then be produced in theresultant closed volume. The force of the atmospheric pressure outsidethe closed volume then causes the cover to deform and contact thecomposite forming materials. This contact forces these materials againstthe surface or cavity walls. After curing of the composite formingmaterials, a composite part having the shape of the surface or the toolbody cavity walls may be produced.

The composite forming materials that may be suitable for formingcomposite parts using the tools comprising carbon foam and HDCF mayinclude those composite forming materials known in the relevant arts.Suitable matrix materials may include, but are not limited to, resins,prepregs, vinyl esters, adhesion films and coatings. Resins may compriseany family of thermoplastic or thermosetting resins, such as phenolicresins, and may be catalyzed. Other examples of suitable matrixmaterials may include epoxy resins. Such resins may be formed from lowmolecular weight diglicidyl ethers of bisphenol A. Depending onmolecular weight, such resins may range from liquids to solid resins,and can be cured with amines, polyamides, anhydrides or other catalysts.Suitable solid resins may be modified, for example, with other resinsand unsaturated fatty acids. Epoxy resins may be particularly suitableas they have good adhesion to fibers and because their thermal expansioncan be tailored to match that of carbon foam and HDCF based tooling whencombined with certain fibers. In addition, their low viscosities areeffective in wetting various reinforcing materials. More specifically,the resins suitable for use in manufacturing composite parts maycomprise any combination of commercially available resins, for example,but not limited to, Dow 330, Gougeon WEST, Gougeon XR02-099-29A, ProSet125, ProSet 135, ProSet 145, and MGS. Also, commercially availableresins that may be useful for tool face materials may comprise, but arenot limited to, for example, PTM&W HT2C, AirTech Toolmaster 2001, JDLincoln L-956, and Vantico RP 4005. Additionally, composite parts may beproduced in the tooling of the present invention using vinyl esters. Thematrix materials useful in the present invention may also encompasscatalysts, hardeners, and other curing agents used to initiatepolymerization or hardening of the matrix material system. For thepurposes of this specification, suitable matrix materials will herein becollectively referred to as resins.

Prepregs are also suitable for use as composite forming materials forthe production of composite parts using the tooling of the presentinvention. Prepregs is an abbreviation of preimpregnated and includesthose reinforcing materials that are combined with an uncured matrixmaterial prior to placement on the tool face. Prepregs may comprise anycombination of mat, fabric, nonwoven material and roving with resin.Typically, these are usually cured to the B-stage, ready for molding.Further examples of prepreg material include, but are not limited to,mixtures, such as, JD Lincoln L-526, epoxy/carbon mixtures, such as, JDLincoln L-956, ACG, and AirTech Toolmaster, and epoxy/glass mixtures,such as, Bryte, and the like. Also, commercially available prepregmaterial used for tool face materials may comprise epoxy/carboncombinations, for example, JD Lincoln L-956, ACG, and AirTechToolmaster.

Moreover, composite parts may be produced in the tooling of the presentinvention using adhesion films. Adhesion films are a thin, dry film ofresin, usually a thermoset, used as an interleaf in the production oflaminates such as plywood. Heat and pressure applied in the laminatingprocess may cause the film to bond both layers together. Somecommercially available adhesion films include, but are not limited to,JD Lincoln L-313 Epoxy, SIA-MA-562, and SIA-PL-7771 FR.

Reinforcing materials used in the composites produced in the tooling ofthe present invention may include any of those know in the relevantarts. Such materials may include, but are not limited to, carbons(including graphite), Kevlar, arimide, glass and the like in forms thatinclude, for example, fibers, including unidirectional fibers andchopped fibers, woven materials, and non-woven materials, and clothmaterials. Particulate reinforcements may also be used.

Reinforcing structures can also be added to the composite formingmaterials while these materials are positioned on the tool face. Suchreinforcing structures may, for example, strengthen the resultingcomposite part and/or form the basis for attaching the composite part toresult in an assembly. These reinforcing structures may include formssuch as bars, tubes, sheets, screens, flats, plates, and the like, ofany specific geometric configuration. Materials of which suchreinforcing structures are composed may include essentially any solidmaterial, in some embodiments exhibiting appreciable strength, having asuitable compatibility with both the composite forming materials and anyassociated curing conditions. Such materials may include metals,ceramics, plastics, wood, glass, previously cured composites, graphite,carbon foam, HDCF, and the like. In practice, reinforcing structures maybe immersed in, or placed against a surface of, the composite formingmaterials on the tool face. After curing of the composite formingmaterials, the reinforcing structures may be more firmly attached to theresulting composite part by the use of screws, clips, adhesives, and thelike if so desired or required. Specifically, such reinforcingstructures may have CTEs that are substantially similar or identical tothat of the resultant composite part.

Various composite forming techniques may be used in conjunction with thetools of the present invention. These techniques are well know to thoseskilled in the associated arts and include, but are not limited to, handlay up, automated lay up, hand spray up, automated spray up, resintransfer molding (RTM), and vacuum assisted resin transfer molding(VARTM). Additionally, any combination of such methods may also be used.

Resin transfer molding is a method by which liquid thermoset polymericresins are transferred within a volume that may be confined, such as,for example, a cavity or a channel within or on a tool body or tool bodysurface. Reinforcements, such as chopped fibers, may be distributedwithin the resin prior to distribution. Alternatively, a fiberreinforcement may be positioned within the volume, particularly in thearea of the volume defined by a tool face. RTM is typically practiced bytransferring or injecting catalyzed resin, examples of which includepolymers of epoxy, vinyl ester, methyl methacrylate, phenolic, andpolyester into a volume of the tool a least partially defined by a toolface(s). The resins fill the volume and infuse into reinforcingmaterials which have been previously positioned within the volume. Careis exercised in this procedure to prevent the entrapment of gas bubblesas gas bubbles may weaken the resulting composite material. Typicalreinforcements may include fiberglass and carbon fibers.

A vacuum system may also be used to assist in the transfer of the resinin and through the tool volume. This process is called vacuum assistedresin transfer molding. With adequate provision, a vacuum system may beutilized in many composite forming processes. It should be noted thatfor purposes of this specification, a vacuum system is a system capableof reducing the internal gaseous pressure of a closed volume, connectedto the vacuum system, to pressures significantly below ambientatmospheric pressure. That is, a vacuum system will evacuate anenclosure, including a closed volume. Vacuum systems typically consistof a vacuum pump and associated connecting tubing or pipe.

Additionally, the extraction of air from the composite formingmaterials, during forming of the composite part, by use of a vacuumsystem may help insure the dimensional and structural accuracy andprecision of the formed composite part. That is, such air extraction canreduce, or even eliminate, the formation of air bubbles in the resultingcomposite part. Such bubble elimination can result in stronger compositeparts. Air extraction is usually practiced by producing at least apartial vacuum in a closed volume containing the composite formingmaterials. Additionally, the production of a vacuum in such a closedvolume, if that volume is defined by at least one flexible wall orcover, can result in the composite material being compressed, usually bydesign, against the tool face by the action of the environmentalatmospheric pressure on the flexible wall or cover.

More specifically, the closed volume may be formed, for example, byclosing, and sealing, openings, ports and/or borders which have accessto the volume. This may be accomplished with a vacuum bag, including,for example, a sheet of flexible material, a bleeder cloth and a releasefilm placed over and/or below the lay up of composite material on thetool, and the edges of the sheet, which are sealed to create a closedvolume. A vacuum system is connected to the closed volume which containsthe bleeder cloth, release film, and the lay up of the compositematerial. The entrapped air is mechanically worked out of the lay up ofcomposite material and is removed by the vacuum system. The compositepart is then cured over time under controlled temperature and pressureconditions. Depending on the material for forming the composite partand/or the characteristics of the final product, the material forforming the composite part may be cured, at temperatures ranging fromabout ambient temperature to about 400° F. and vacuum pressures rangingfrom about 0 to about 28 in Hg. These ranges are dependent on the typeof resins used. That is, any suitable temperature and/or pressure may beused.

Carbon foam and HDCF may be jointly incorporated into existing compositetools to provide the benefits of the present invention. Suchincorporation may be to up grade, effect repair, or to otherwise providefor any benefit of the present invention. Such incorporation is fullyembodied within the scope of the present invention.

An embodiment of the present invention relates to a tool bodycomprising, at least in part, carbon foam and HDCF, where a surface ofthe HDCF defines a tool face. The HDCF and carbon foam may be selectedsuch that the CTE of the HDCF and carbon foam are substantially similaror essentially equivalent to that of the cured composite which will beformed by the tool. In use, the HDCF tool face is coated with a releaseagent. Composite forming materials, which may be carbon compositeforming materials, are then placed on the tool face to provideessentially uniform coverage of the tool face. The composite formingmaterials may be pressed against the tool face. The composite formingmaterials are then cured at an elevated temperature to provide acomposite, which is then removed from the tool.

Another embodiment of the present invention relates to a tool bodycomprising, at least in part, carbon foam and HDCF wherein a surface ofthe HDCF supports a tool face material. The HDCF is supported at leastin part by the carbon foam. A surface of the tool face material, whichin some embodiments may be a carbon fiber composite, is shaped so as todefine a tool face. The HDCF, carbon foam, and tool face material may beselected such that the CTE of the HDCF, carbon foam, and tool facematerial are substantially similar or essentially equivalent to that ofthe cured composite which will be formed by the tool. In use, the toolface is coated with a release agent. Composite forming materials, whichmay be carbon composite forming materials, are then placed on the toolface to provide essentially uniform coverage of the tool face. Thecomposite forming materials may be pressed against the tool face. Thecomposite forming materials are then cured at an elevated temperature toprovide a composite, which may be a carbon composite, which is thenremoved from the tool.

A further embodiment of the present invention relates to a tool bodycomprising, at least in part, carbon foam and HDCF where the carbon foamis at least partially supported by the HDCF. A surface of the carbonfoam, comprising a least a portion of the tool body, supports a toolface material. A surface of the tool face material, which in thisembodiment is a carbon fiber composite, is shaped so as to define a toolface. The carbon foam, HDCF, and tool face material may be selected suchthat the CTE of the carbon foam, HDCF, and tool face material aresubstantially similar or essentially equivalent to that of the curedcomposite which will be formed by the tool. In use, the tool face iscoated with a release agent. Carbon composite forming materials are thenplaced on the tool face to provide essentially uniform coverage of thetool face. The composite forming materials may be pressed against thetool face. The composite forming materials are then cured at an elevatedtemperature to provide a carbon composite, which is then removed fromthe tool.

Reference will now be made in detail to other embodiments of the presentinvention, examples of which are illustrated in the accompanyingFigures. Various aspects of these embodiments can be combined under theteachings of the present invention to provide additional examples whichare not specifically laid forth. Therefore these embodiments areintended to be only illustrative of the present invention and are not tobe considered limiting of that invention.

FIG. 1 illustrates a tool and a system for fabricating at least onecomposite part, according to an embodiment of the invention. FIG. 1illustrates a cross-sectional representation of a reusable tool 10having a tool face 11. The body of this tool is comprised of a piece ofcarbon foam 12 and a piece of HDCF 13. The carbon foam piece 12 and theHDCF piece 13 are bonded together at their area of mutual contact 14using an adhesive, resin, or other similar bonding material. The carbonfoam nearest the tool face may be partially or completely filled with afilling material.

Composite parts may be produced using such a tool face by first coatingthe tool face with a release compound. Alternatively, the tool face maybe covered with a parting film or sheet. Composite forming materials maythen be placed on the tool face or parting film covering the tool face.These composite forming materials are positioned, mechanically ormanually, over the area of the tool face or parting sheet covering thetool face such that, in some embodiments, an essentially uniformdistribution of these materials is obtained. The composite formingmaterials may be pressed against the tool face or parting sheet coveringthe tool face. This pressing may be performed to insure the compositeforming materials conform to the configuration of the tool face. Also,if the tool face is unfilled carbon foam, such pressing may impart sometype of patterning, representative of the unfilled carbon foam cells onthe tool face, to the tool face defined surface of the composite part.

The composite forming materials are then cured to produce a composite,i.e. a composite part, having the form imparted by the tool face.Heating of the composite forming materials may be preferred or requiredfor some composite forming materials to effect curing. Heating may beaccomplished by use of an autoclave, oven, individual heating elements,and/or other like heating devices. Individual heating elements can beexternal to, or internal to (i.e. embedded within), the tool body. Aswas discussed previously, heating will effect changes in the dimensionsof all the heated materials. The magnitudes of such dimensional changesare dependent on the CTEs of the individual materials. For this, and allthe examples included in this specification, the CTE of the tool faceand of the resultant composite part are preferably similar oressentially equivalent, such as may be the case if the resultantcomposite part is a CFC. Additionally, in some embodiments, the CTE ofthe tool face and carbon foam and HDCF of the tool body may be similaror essentially equivalent to that of the resultant composite part. Ifthe CTE of the composite part is not similar or essentially identical tothat minimally of the tool face, the size of the composite part may notconfirm to the desired critical dimensions. Additionally, if the CTE isgreater than that of the tool face, the component part may become“locked” on the tool face with separation from the tool face withoutdamage to the tool face or composite part being difficult if notimpossible.

FIG. 2 illustrates another embodiment of a tool and a system forfabricating at least one composite part. FIG. 2 illustrates across-sectional representation of a reusable tool 20 having a tool face21. The body of this tool is comprised of a piece of carbon foam 22 anda piece of HDCF 23. The carbon foam piece 22 and the HDCF piece 23 arebonded together at their area of mutual contact 24 using an adhesive,resin, or other similar bonding material. The HDCF nearest the tool facemay be partially or completely filled with a filling material.

Such a tool, having a tool face defined by a surface of HDCF, may beused for the production of composite parts in much the same manner asdescribed above with respect to FIG. 1.

FIG. 3 illustrates a further embodiment of a tool and a system forfabricating at least one composite part. FIG. 3 illustrates across-sectional representation of a reusable tool 30 having a tool face31. The body of this tool is comprised of more than one piece of carbonfoam 32A and 32B and more than one piece of HDCF 33A, 33B, and 33C. Thecarbon foam pieces 32A and 32B and the HDCF pieces 33A, 33B, and 33C arebonded together at their areas of contact 34A, 34B, and 34C using anadhesive, resin, or other similar bonding material. The HDCF nearest thetool face may be partially or completely filled with a filling material.

Such a tool, having a tool face defined by a surface of HDCF, may beused for the production of composite parts in much the same manner asdescribed above with respect to FIG. 1.

FIG. 4 illustrates still another embodiment of a tool and a system forfabricating at least one composite part. FIG. 4 illustrates across-sectional representation of a reusable tool 40 having a tool face41. The body of this tool is comprised of more than one piece of carbonfoam 42A, 42B, and 42C and more than one piece of HDCF 43A, and 43B. Thecarbon foam pieces 42A, 42B, and 42C and the HDCF pieces 43A and 43B arebonded together at their areas of contact 44A, 44B, and 44C using anadhesive, resin, or other similar bonding material. The carbon foamnearest the tool face may be partially or completely filled with afilling material.

Such a tool, having a tool face defined by a surface of carbon foam, maybe used for the production of composite parts in much the same manner asdescribed above with respect to FIG. 1.

FIG. 5 illustrates yet another embodiment of a tool and a system forfabricating at least one composite part. FIG. 5 illustrates across-sectional representation of a reusable tool 50 having a tool face51. The body of this tool is comprised of a piece of carbon foam 52 anda piece of HDCF 53. The carbon foam piece 52 and the HDCF piece 53 arebonded together at their area of contact 54 using an adhesive, resin, orother similar bonding material. A surface of the carbon foam 55 iscovered with a tool face material 56. The tool face material may be aCFC or other tool face materials as discussed above. A surface of thistool face material provides the tool face 51.

Such a tool, having a tool face defined by a surface of a tool facematerial, may be used for the production of composite parts in much thesame manner as described above with respect to FIG. 1.

FIG. 6 illustrates still another embodiment of a tool and a system forfabricating at least one composite part. FIG. 6 illustrates across-sectional representation of a reusable tool 60 having a tool face61. The body of this tool is comprised of a piece of carbon foam 62 anda piece of HDCF 63. The carbon foam piece 62 and the HDCF piece 63 arebonded together at their area of contact 64 using an adhesive, resin, orother similar bonding material. A surface of the HDCF 65 is covered witha tool face material 66. The tool face material may be a CFC or othertool face material discussed above. A surface of this tool face materialprovides the tool face 61.

Such a tool, having a tool face defined by a surface of a tool facematerial, may be used for the production of composite parts in much thesame manner as described above with respect to FIG. 1.

FIG. 7 illustrates an additional embodiment of a tool and a system forfabricating at least one composite part. FIG. 7 illustrates across-sectional representation of a reusable tool 70 having a tool face71. The body of this tool is comprised of at least two pieces of carbonfoam 72 and 73 and at least two pieces of HDCF 74 and 75. The carbonfoam pieces 72 and 73 and the HDCF pieces 74 and 75 are bonded togetherat their areas of contact 76, for example, using an adhesive, resin, orother similar bonding material. A surface of a piece of the carbon foam73 and a surface of a piece of the HDCF 75 are covered with a tool facematerial 77. The tool face material may be a CFC or other tool facematerial as discussed above. A surface of this tool face material 77, asurface of the carbon foam piece 72, and a surface of the HDCF piece 74provide a tool face 71.

Such a tool, having tool face comprising the surface of a tool facematerial, a surface of a carbon foam piece, and a surface of a HDCFpiece, may be used for the production of composite parts in much thesame manner as described above with respect to FIG. 1.

FIG. 8 illustrates another embodiment of a tool and a system forfabricating at least one composite part. FIG. 8 illustrates across-sectional representation of a reusable tool 80 having a tool face81. The body of this tool is comprised of three pieces of carbon foam82A, 82B, and 82C and four relatively thin pieces of HDCF 83A, 83B, 83C,and 83D. The carbon foam pieces 82A, 82B, and 83C and the HDCF pieces83A, 83B, 83C, and 83D are bonded together at their areas of mutualcontact 84A, 84B, and 84C, for example, using an adhesive, resin, orother similar bonding material. The HDCF nearest the tool face may bepartially or completely filled with a filling material. Such a tool,having a tool face defined by a surface of the HDCF, may be used for theproduction of composite parts in much the same manner as described abovewith respect to FIG. 1.

In certain embodiments, the design of the tool is such that the toolbody volume is primarily carbon foam while the tool face is defined byrelatively thin pieces of HDCF incorporated into the tool body. Thistype of tool body design may provide for a very rigid tool body and aHDCF tool face (which may be dense and hard) while not encountering thenegative aspects (such as weight and cost) associated with a tool bodycomprised essentially entirely of HDCF.

FIG. 9 illustrates yet another embodiment of a tool and a system forfabricating at least one composite part. FIG. 9 illustrates across-sectional representation of a reusable tool 90 having a tool face91. The body of this tool is comprised of three pieces of carbon foam92A, 92B, and 92C and four relatively thin pieces of HDCF 93A, 93B, 93C,and 93D. The carbon foam pieces 92A, 92B, and 92C and the HDCF pieces93A, 93B, 93C, and 93D are bonded together at their area of mutualcontact 94A, 94B, and 94C, for example, using an adhesive, resin, orother similar bonding material. The HDCF nearest the tool face may bepartially or completely filled with a filling material. The outersurfaces, not including the tool face, of the tool body may be coveredwith a covering material 95. The covering material may include, but isnot limited to, composites, polymeric materials, materials used as toolface materials, metals, ceramics, and structural materials. Suchcovering materials may be, for example, bonded to the tool body,mechanically attached to the tool body, or held in the desired positionrelative to the tool body by mechanical means. In some embodiments, suchcovering materials may comprise polymeric materials that are infusedinto non-tool face surface(s) of the tool body. Covering materials mayserve to provide some degree of mechanical protection to the non-toolface surface(s) of the tool body. In other embodiments, coveringmaterials may serve to seal, or otherwise make impermeable, non-toolface surface(s) of the tool body. Such a tool, having a tool facedefined by a surface of HDCF, may be used for the production ofcomposite parts in much the same manner as described above with respectto FIG. 1.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A tool for the production of at least one composite part, the toolcomprising a tool body having a tool face wherein the tool body iscomprised of at least one piece of carbon foam and at least one piece ofhigh density carbon foam having a thermal conductivity between about 5to 70 W/mK, and wherein the tool face defines a surface that is a threedimensional negative mirror image of a surface of the at least onecomposite part, wherein the carbon foam has a density ranging from about0.05 g/cc to about 0.8 g/cc and the high density carbon foam has adensity ranging from above about
 1. g/cc to about 1.6 g/cc.
 2. The toolof claim 1 wherein a surface of said tool body defines a tool face, andwherein a portion of said tool face is at least partially a surface ofsaid carbon foam comprising said tool body.
 3. The tool of claim 1,wherein a surface of said tool body defines a tool face, and wherein aportion of said tool face is at least partially a surface of said highdensity carbon foam comprising said tool body.
 4. The tool of claim 1,wherein at least a portion of cells of said carbon foam are at leastpartially filled with a filling material.
 5. The tool of claim 1,wherein at least a portion of the porosity of said high density carbonfoam is at least partially filled with a filling material.
 6. The toolof claim 4, wherein said filling material is at least one of a curedresin, a pitch, a cured ceramic, a carbonized resin, or a carbonizedpitch.
 7. The tool of claim 5, wherein said filling material is at leastone of a cured resin, a pitch, a cured ceramic, a carbonized resin, or acarbonized pitch.
 8. The tool of claim 1, wherein the coefficient ofthermal expansion of said tool face is substantially similar to thecoefficient of thermal expansion of the composite part.
 9. The tool ofclaim 1, wherein at least a portion of said carbon foam comprising saidtool body at least partially supports a tool face material.
 10. The toolof claim 1, wherein at least a portion of said high density carbon foamcomprising said tool body at least partially supports a tool facematerial.
 11. The tool of claim 9, wherein at least a portion of asurface of said tool face material comprises at least a portion of atool face.
 12. The tool of claim 10, wherein at least a portion of asurface of said tool face material comprises at least a portion of atool face.
 13. The tool of claim 9, wherein said tool face material isselected from the group consisting of metals and ceramics.
 14. The toolof claim 10, wherein said tool face material is selected from the groupconsisting of metals and ceramics.
 15. The tool of claim 9, wherein saidtool face material is selected from the group consisting of metal,silicon carbide, and zirconia ceramics.
 16. The tool of claim 10,wherein said tool face material is selected from the group consisting ofmetal, silicon carbide, and zirconia ceramics.
 17. The tool of claim 9,wherein said tool face material is selected from the group consisting ofa cured resin, a fiber composite, and a particulate composite.
 18. Thetool of claim 10, wherein said tool face material is selected from thegroup consisting of a cured resin, a fiber composite, and a particulatecomposite.
 19. The tool of claim 9, wherein said tool face materialcomprises a carbon fiber composite.
 20. The tool of claim 10, whereinsaid tool face material comprises a carbon fiber composite.
 21. The toolof claim 1, the high density carbon foam has a density ranging fromabout 1.3 g/cc to about 1.6 g/cc.
 22. A method for producing at leastone composite part, comprising the steps of: providing a tool bodyhaving a tool face, wherein said tool body is comprised of carbon foamand high density carbon foam adhered together, and wherein the tool facedefines a surface that is a three dimensional negative mirror image of asurface of the at least one composite part, wherein the carbon foam hasa density ranging from about 0.05 g/cc to about 0.8 g/cc and the highdensity carbon foam has a density ranging from above about
 1. g/cc toabout 1.6 g/cc, and wherein the high density carbon foam has a thermalconductivity between about 5 to 70 W/mK; placing composite formingmaterial on said tool face; and curing said composite forming materialthereby producing the composite part.
 23. The method of claim 22,wherein at least a portion of said tool face is a surface of said carbonfoam comprising said tool body.
 24. The method of claim 22, wherein atleast a portion of said tool face is a surface of said high densitycarbon foam comprising said tool body.
 25. The method of claim 22,wherein said composite forming material is a mixture of a resin and atleast one selected from the group consisting of a particulatereinforcing material and a fibrous reinforcing material.
 26. The methodof claim 22, wherein the composite part is a carbon fiber compositepart.
 27. The method of claim 22, further comprising the step of placinga parting film between said composite forming materials and said toolface prior to placing composite forming material on said tool face. 28.The method of claim 22, further comprising the step of coating at leasta portion of said tool face with a release agent prior to placingcomposite forming material on said tool face.
 29. The method of claim22, wherein at least a portion of cells of said carbon foam forming theat least a portion of said tool body are at least partially filled witha filling material.
 30. The method of claim 22, wherein at least aportion of the porosity of said high density carbon foam forming the atleast a portion of said tool body are at least partially filled with afilling material.
 31. The method of claim 22, wherein at least a portionof said tool face comprises a surface of a tool face material, whereinat least a portion of said tool face material is supported by saidcarbon foam.
 32. The method of claim 22, wherein at least a portion ofsaid tool face comprises a surface of a tool face material, wherein atleast a portion of said tool face material is supported by said highdensity carbon foam.
 33. The method of claim 31, wherein said tool facematerial is selected from the group consisting of metals and ceramics.34. The method of claim 31, wherein said tool face material is selectedfrom the group consisting of metal, silicon carbide, and zirconiaceramics.
 35. The method of claim 31, wherein said tool face material isselected from the group consisting of a cured resin, a fiber composite,and a particular composite.
 36. The method of claim 31, wherein saidtool face material comprises a carbon fiber composite.
 37. The method ofclaim 32, wherein said tool face material is selected from the groupconsisting of metals and ceramics.
 38. The method of claim 32, whereinsaid tool face material is selected from the group consisting of metal,silicon carbide, and zirconia ceramics.
 39. The method of claim 32,wherein said tool face material is selected from the group consisting ofa cured resin, a fiber composite, and a particular composite.
 40. Themethod of claim 32, wherein said tool face material comprises a carbonfiber composite.